package com.utils;

import java.math.BigDecimal;

/**
 * Created with IntelliJ IDEA.
 * <p>
 * User: wanglulu
 * <p>
 * Date: 13-10-14
 * <p>
 * Time: 下午6:21
 * <p>
 * To change this template use File | Settings | File Templates.
 */

public class MapUtils {

    private static final double EARTH_RADIUS = 6378.137;

    private static double rad(double d) {

        return d * Math.PI / 180.0;

    }

    /**
     * 根据两点间经纬度坐标(double值)，计算两点间距离，单位为米
     *
     * @param lng1
     * @param lat1
     * @param lng2
     * @param lat2
     * @return
     */

    public static Double GetDistance(Double lng1, Double lat1, Double lng2, Double lat2) {

        if (null == lng1 || null == lat1 || null == lng2 || null == lat2) {

            return null;

        }

        double radLat1 = rad(lat1);

        double radLat2 = rad(lat2);

        double a = radLat1 - radLat2;

        double b = rad(lng1) - rad(lng2);

        double s = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(a / 2), 2) +

                Math.cos(radLat1) * Math.cos(radLat2) * Math.pow(Math.sin(b / 2), 2)));

        s = s * EARTH_RADIUS;

// s = Math.round(s * 10000) / 10000;

        BigDecimal decimal = new BigDecimal(s * 1000);

        if (null != decimal) {

            return decimal.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();

        }

        return null;

//return s;

    }

    public static void main(String[] args) {

        double distance;

        distance = GetDistance(121.43106979, 31.36955239, 121.43332284, 31.36636445);

        System.out.println("Distance is:" + distance);

    }

}
